Study on the Foaming Behaviors of PBS and Its Modification with PA6IcoT Assisted by scCO₂

The foaming behaviors of a semicrystalline poly(butylenes succinate) (PBS) and its blends with an amorphous semiaromatic nylon poly(hexamethylene (iso‐co‐tere)phthalamide) (PA6IcoT) assisted by supercritical CO₂ (scCO₂) as blowing agent at 110–130 °C and 16–24 MPa are investigated. The results show that the average cell diameter and cell density of the pure PBS foam obtained at 24 MPa and 120 °C are 46 μm and 1.6 × 10⁷ cells cm⁻³, respectively. The cell coalescence is prevented and heterogeneous nucleation is induced in the presence of PA6IcoT in the physical blends (mPBS), resulting smaller cell size as 12 μm and higher cell density as 1.6 × 10⁹ cells cm⁻³ in the foams at 24 MPa and 120 °C. The reactive blends (rPBS) with PA6IcoT prepared by 2,2‐(1,3‐benzene)bis(2‐oxazoline) (PBO) as chain extender are promising for higher complex viscosity and lower crystallinity, resulting in higher melt strength and better foamability. The rPBS foams with cell size as small as 8 μm and cell density as high as 2.0 × 10⁹ cells cm⁻³ are obtained at 24 MPa and 120 °C.